Naphthalate-based bottles beckon (sidebar)

"If you'd asked me three or four years ago if I considered that PEN or any other material for that matter would take a share of the PET market, I would have said the economics would prevent it," Michael Koch of Krupp Corpoplast (Hamburg, Germany) told the audience at Bev-Pak Americas '95 in April. And what does he think now about PEN and related naphthalate-based resins? "We're right in front of a major breakthrough." Koch then went on to present Krupp's laboratory cost comparison of four different container types, each made from four different materials: with straight PET and with three different naphthalate compositions. Container #1 was a 500-mL single-serve beverage bottle; #2, a 32-oz ketchup bottle; #3, a 1.5-L hot washable, refillable and hot-refillable (HRHF) bottle (described by Koch as "the most innovative application"); and #4, a 1.5-L one-way heat-set hot-fill container. The table shown at right summarizes the key findings of Krupp's test. Worth noting: * Because NDC-based materials show a slightly higher natural stretch ratio, blow molding cycle times came down for all four bottles when NDC was part of the resin composition. * As expected, in all four bottle types, desirable performance characteristics-thermal stability, gas and UV barrier, strength-improved when NDC was part of the composition. * The single-serve container made of 8% PEN blended with 92% PET leads to a slight container cost improvement compared to straight PET because it weighs 5 g less. * When NDC was part of the resin composition at any of the levels studied, both the HRHF container and the one-way hot-fill bottle offered significant cost advantages over PET containers. * The ketchup bottle looks promising at an 8% PEN blend level. "PEN is an interesting candidate in this application," said Koch. The two bottles that most intrigued Koch were the HRHF and the one-way hot-fill, because for both bottles, the use of a naphthalate-based resin reduced container cost per thousand. "I think this could have a considerable impact on the markets for hot-fill, heat-set containers," Koch told his audience. Bev-Pak Americas '95, held April 24-25 in Tarpon Springs, FL, was sponsored by Directions 21 (Sarasota, FL).